1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to accessory modules for electrical switching apparatus, such as circuit breakers. The invention also relates to strain relief mechanisms for circuit breaker accessories.
2. Background Information
Electrical switching apparatus, such as circuit breakers, as well as transfer switches, network protectors and the like, are often equipped with accessories such as, for example and without limitation, auxiliary switches, shunt trip devices, under voltage release devices, and bell alarms. Such devices can be employed in a variety of ways to provide signals indicating certain conditions within the apparatus and/or to initiate a change in status of the apparatus such as, for example, to trip open the separable contacts of the apparatus in response to an electrical fault condition (e.g., without limitation, current overload; short circuit; abnormal voltage).
In view of the increasing market trend to reduce the overall size of the circuit breaker, the space which is available within the circuit breaker housing is limited. In addition to size constraints, the location available for mounting accessories within the circuit breaker can also be problematic. For example, some locations for mounting the accessories in the circuit breaker have limited access for installing the accessories and, in some instances, blind installation is required, wherein it is not possible to see the accessory to mount the accessory within the circuit breaker housing. As a result, incorrect installation and/or damage to the accessories can result, and safety features of the circuit breaker can be adversely affected.
Additionally, the accessories typically include an enclosure and sometimes have a number of electrical conductors (e.g., wires) extending outwardly from the enclosure. The accessory enclosure typically consists of opposing molded portions which are fastened together using a plurality of separate fasteners. It is desirable to minimize the number of separate parts and associated cost of the accessories, for example, by eliminating at least some of the fasteners and improving upon the manner in which the portions of the accessory enclosure are fastened.
Furthermore, the electrical conductors are susceptible to damage. Accordingly, it is also desirable to provide strain relief for the electrical conductors, for example, in order to resist a pulling force on the electrical conductors which could compromise the integrity of the electrical connection.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in accessory modules and in strain relief mechanisms therefor.